Possible Clues:

• Weapon on submarine I had submerged in river
• The way to study clothing and forward it on?
• One might be goin' fishin' with it - all three of it
• Pointedly to ride if it's gone bad at last
• Seems I'd be fishing with this in the river
• Be carried among explosive for Neptune to have in hand
• Neptune's or Britannia's spear
• Trot in explosive missile
• Be at anchor, protected by explosive weapon
• Red tint (anag.)